Conventional film cameras have been replaced with, for example, camera modules for portable terminals, Digital Still Cameras (DSCs), camcorders, and PC cameras (image pickup devices attached to personal computers), which use small solid image pickup elements such as, for example, CCDs and CMOSs. These image pickup devices are becoming much thinner and smaller.
According to this trend, although light receiving elements, such as Charge Coupled Devices (CCDs), mounted in smaller image pickup devices, are being reduced in size, a part that occupies the greatest volume of the image pickup device is an image pickup lens part.
Accordingly, a constituent element that is becoming the greatest obstacle to realizing smaller and thinner image pickup devices is an image pickup lens, which forms an image of an object.
Here, it is required not only to simply implement a small image pickup lens, but also to achieve high performance of the image pickup lens in order to keep up with the higher performance of the light receiving element. However, a smaller image pickup lens is unavoidably closer to the light receiving element, which problematically causes light to be obliquely incident on the image forming surface of the image pickup device, thereby resulting in insufficient condensing of the image pickup lens and the potential of extreme variation in the brightness of an image from the center to the periphery of the image.
Increasing the number of lenses in consideration of the problems described above unavoidably increases the size of the image pickup device and is problematic in terms of the cost.
Therefore, there is a need to implement a high performance image pickup lens while considering manufacturing costs.